DIY Audio Projects Forum

Thnk you for reply, last weekend i tried something and here is results
- Replaced coax cable in input signal wire like you said - nothing change, i notice when i touch to the cable or input caps the noise go heavier.
- Then i replaced input jack cable with a coax calbe too, the noise reduce abit.
- This buzz noise complete disapear when i touch to the volume pot (which shorted to pot gnd), but in my country there have no any ground system in house, and my department on 4th floor ...
- I thought about volume pot, then i remove volume pot (left input signal with 100 ohm resistors) and yea, buzz noise gone. The only noise i can notice is small hum (maybe from my power which i reduted it by diode bridge). Buzz noise still apear when i touch to input wire or input caps. So is it all about my volume pot have bad quality ????
- Larger power caps i put to power, the hum go smaller but still noticed when source silent, the problem is i feel with about 4700uf, the sound quality gone so heavy and not clear , after few calculator i found on internet, i plan make a lc filter (3mh coil inductance and 1000uf caps) hope it will go well.
Srry for my bad english

Recently completed this scheme, adding a 12V lithium battery, orange LED under the lamp for more drama and turning the lamp in parallel with the board for portability. Passing capacitors put 6.8mF. The result is very pleasing, the input signal does not distort, but makes it natural for listening. Now I cant find a power supply that does not add noise, so I only use the battery and the power supply to charge.

Hi! I have build with ecc81 (I have a lot in the drawer). It is a good project.
Bye.

Thanks the interesting project sharing, I had build my own kits and the sound is amazing.
There are some test piece I record with this kits to share in the link. Although the tube only bias with 12V, the dynamic performance still excellent.

1.The violin sound quality test
https://youtu.be/G5z4hbskJOY

2.The dynamic performance test
https://youtu.be/GPitrBcEXSg

Hi,

I built this amp with 2 single triodes 12a6 types as I didnt have any twin triodes.
Worked great once I fixed the human errors like wiring the first tube socket in reverse and smoking a resistor:)

Tried with the adjust pot and compared with the fixed resistor. Ended up going with the fixed.

No enclosure yet, just wired up on 2 small breadboards side by side.

I can imagine it'll look pretty cool with the twin tubes once in an enclosure.

Used an old 12v ps from an external CD ROM after a hum issue with a 12v walwort.

Trying to decide between wood, aluminum or plexi for the enclosure.

Anyway, thanks to the builder/designer Rogers for a great job and for making the plan available to us homebrewers.

Cheers

I'm new to the forum today so hi everyone!
anyway, I have came across this circuit a while ago and think its ideal for my first valve project. However I wonder if replacing the LM317 with a mosfet based CSS would be an improvement? I have simulated this in LTspice and it does work, however I am a little surprised at how low the current draw is at 80mA and the fact that increasing the current (by decreasing the value of R6) actually increases distortion which is at 0.70THD in my circuit, seems high to me but I'm aware that valves are more prone to second harmonic distortion.

My LTspice circuit:
https://i.ibb.co/7x3V694/my-valve.png

Does this distortion level seem accurate? and is the CCS configured correctly?